Question: What is the difference between explode and major options within Dialog thesauri?

Answer: Explode and Major are two options available within the Dialog thesauri to assist in retrieving relevant articles from those databases.



If you select “explode” option, this will retrieve all articles indexed with that particular term and all narrower terms associated with it. (Please see this document for a further discussion on explode function)

However, by selecting the “major” option, this will only retrieve that specific indexed term which has also been assigned as “major”. (Please see this document for a further discussion on major function)

Thus, the difference between “explode” and “major”, is that by using “explode”, this will include all relevant terms, including those that have been assigned as “major”.

However, the reverse is not true, if you limit your search to “major”, you will only retrieve articles specifically associated with “major”


This can be illustrated by searching the following command:

MJMesh.exact(“Drug Therapy”) or for Embase MJEMB.exact("Drug therapy")

The following record will not be retrieved:

Title: Moxibustion for the side effects of surgical therapy and chemotherapy in patients with gastric cancer: A protocol for systematic review and meta-analysis




To that end, it is recommended that you only select the “Major” option when trying to limit a large number of results for a specific subject term.

However, by searching the Mesh.exact.explode or emb.exact.explode fields, these will also retrieve articles that have thesaurus terms indexed with “Major”.